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PRUNING FRUIT PLANTS
R. J. BARNETT
INTRODUCTION
General Requirements of Modern Orcharding.-Modern orcharding involves three production operations of first rank: Spraying, pruning, and soil mamagement. A good deal of misunderstanding is current regarding the relative importance of these three primary operations, and results are frequently credited to one or another of them that cannot be so ascribed under controlled conditions.
But it may be taken as a general rule that lack of care regarding any
of these three will greatly reduce the value of the orchard and the
crop. These three operations are closely related and demand the
grower's attention, each in its proper degree and season. All being
essential to the success of the undertaking, none can be placed in a
dominant position over another. Good spraying and careful soil
management combined with skillful pruning constitute the only
sound foundation for successful fruit production.
Definition of Pruning.-Pruning may be defined as the removal
of a part of a plant for the purpose of increasing the economic value
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of the remainder. This increase in value may be merely the greater
probability of the plant’s living; it may consist in the building of a
larger or stronger tree or bush; fruitfulness may be increased; or it
may be merely an aid to other orchard operations, as spraying and
harvesting. Without exception, however, the grower does better
pruning when he understands the particular purposes toward which
his efforts are directed and the physiological effects which may be expected to follow whatever cutting he does.
Bearing Habits of Fruit Trees.-The grower must understand,
also, something of the method of fruit bearing of the plants which he
prunes. He should know apple and pear fruit spurs and realize that
they are the tree’s machinery for fruit production; that two or more
years are required for their development; that they will be unfruitful, or even die, if overshaded; and that when once lost on any part
of the tree they can never be replaced there but must be produced
further out on the tree and, therefore, be less valuable. I n contrast
with this habit, that of the peach and of some of the sour cherry
varieties may be mentioned. With them the principal part of the
crop is borne from buds on the twig growth of the preceding summer,
and so the production of twigs must be encouraged. Still another
method of fruit bearing is to be found in the case of the grape, the
bramble, the persimmon, and the quince. None of these plants carry
separate fruit buds over winter, but all bloom and bear their fruit
on shoot growth of the current season, which arises from lateral buds
formed the preceding summer. An accurate conception of such facts
is a necessary part of the working knowledge of one who would prune
fruit plants intelligently. Some of these methods of fruit bearing are
illustrated in figure 1.
Individuality of Fruit Trees.-A clear understanding of the fact
that both varieties and trees within the variety have individuality
and that each requires special treatment is of great use to the pruner.
A system which proves successful with the Jonathan apple might not
apply in the case of an upright-growing apple tree like the Rome; so,
although something resembling a system of procedure in pruning
may well be adopted, the worker must constantly keep in mind the
necessity of adapting his “system” to the peculiarities of varieties
and even of individual trees.
Some Definitions.-In order to learn about pruning from the
printed page the writer and the reader must agree regarding the
meaning of terms used in describing the process. The collar of the
tree is the point of union between the root and the trunk. The trunk
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extends from the collar to the first subdivision of branches. Framework or scaffold branches are the first series above the trunk and
subdivide into the secondary branches. The leader in a fruit tree is
the central, upright-growing shaft, a direct continuation of the trunk
through the framework. I n general, the fruit-bearing wood of the
tree is beyond the secondary branches. It may be fruit spurs borne
laterally on wood two or more years old, or it may be twigs. Twigs
may be defined as the last season’s terminal growths, and, aside
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from spurs, they are the only leaf-bearing organs. Figure 2 will
serve to illustrate these definitions.
There are three principal operations connected with pruning:
Heading back, thinning out, and the removal of large branches.
Heading back consists of cutting off a portion of a twig or branch.
It more commonly applies to twigs and is a part of the training of
young trees. Thinning out refers t o the removal of twigs or small
branches which are growing too close together. It is practiced
throughout the life of the tree. Large branches are removed when
they become broken, diseased, or crowded, and in rejuvenation
pruning.
Heavy pruning of fruit trees may be considered as any pruning
in which wood equal to one-fourth or more of the annual twig growth
is removed, while light pruning would be the removal of wood
amounting to less than one-fourth of the annual twig growth. A
third class, medium pruning, might be made, and would include the
removal of one-eighth to one-fourth of the annual growth. These
last definitions are somewhat arbitrary and the amounts named relate to trees which have had regular attention in the way of pruning
and are making normal growth.
Moderation Recommended in Pruning.- Fruit growers have
suffered severe losses due to using extreme methods in pruning. Too
heavy pruning upsets the balance between the top of the tree and
the root system and results in various ill effects, such as unduly delaying the establishment of fruit production, the dwarfing of the
tree, and, usually, its earlier decline and death. Neglect of pruning
and too light pruning are no less injurious. They lead to overheight
of trees, making picking and spraying more expensive; to undue
density of top and consequent poor color of fruit; t o overbearing, a
cause of small fruit and of the biennial habit; and to a general dominance of the vegetative over the reproductive functions of the trees
during the middle period of their lives. For these reasons the medium course in pruning is recommended.
Large trees are desirable but they must not be so large as greatly
to increase the expense of the orchard operations. Vigorous-growing
trees are the most valuable, but they must not be so vigorous in wood
growth as to defeat the object for which they are grown; that is,
fruit yield. Productive, heavy-bearing trees are requisite for profit,
but they should not be so fruitful that they bear themselves to death
in a few years, as occasionally happens.
Moderate annual pruning is of vastly greater value than irregular,
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heavy pruning. The best pruning is that which is done in the light
of a knowledge of its probable results; of the physiological principles
which underlie the work; of the local climatic and soil influences; of
kind and varietal peculiarities; and of the importance of the regular,
well-planned application of this knowledge. Pruning so done assumes a value which entitles i t t o rank as equal in importance with
spraying and soil management.
GENERAL DIRECTIONS
The art of pruning fruit trees can be best comprehended if the
discussion of it, as well as the actual work, be divided into two
rather definite parts. The first of these, which would include all
pruning done between the time the trees are set and the time they
come into bearing, may be called “Pruning for Tree Building.” This
process is, in many ways, in sharp contrast with the subsequent
phase, which may be termed “Pruning for Tree Maintenance and
Fruit Production.”
PRUNING FOR TREE BUILDING
Building the Framework.- The object which should be in the
mind of a grower while pruning for tree building should be the production of trees that are strong; that are large though low; and that
will come into bearing at a proper age. The mechanical strength of
a tree, its ability to support a heavy load of fruit, depends on two
principal features: (1) The correct formation of the framework,
and (2) the stockiness of the wood. The arrangement of the low
framework limbs is usually determined a t the time of the second
pruning following the graft. Care a t this pruning to select branches
that are evenly spaced around the trunk and that are distributed
over a vertical distance of eight inches or more usually will yield a
tree which will not split a t this point. However, the preservation of
a central leader for a number of years still further strengthens this
weakest part of most fruit trees. Stockiness of branch is encouraged
by heading back combined with any treatment which will increase
the vegetable activity of the tree.
Pruning for Size.-Heavy yields of fruit are obtained only from
large trees. The avoidance of over pruning is the principal precaution to be observed in order to produce such trees, provided the soil
is fertile. It is probable that no pruning a t all would be the treatment which would result in the largest trees, but they would be defective in so many ways that this practice has little else to recommend it. Persistent heavy pruning dwarfs fruit trees because it
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greatly reduces the total leaf area of the tree, and consequently the
elaboration of plant food. Large trees must be prevented from becoming too high by judicious heading back of upright-growing
branches and by encouraging, through lighter pruning, those which
tend toward the horizontal.
Pruning and Fruit Bearing.-The age a t which fruit trees begin
to bear is largely an innate characteristic and can be influenced by
pruning within only rather narrow limits. I n a general way, heavy
pruning delays the beginning of fruit production because i t prevents
storage of starch early in the growing season and diverts the activities of the tree to the production of wood to replace that removed,
especially if this heavy prunning is done during the dormant season.
However, light pruning, or even no pruning, seems to have but little
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effect in hastening fruit bearing-the kind of fruit, variety, soil, and
climate probably being the principal factors governing early maturity.
The First Pruning.-In most parts of Kansas one-year-old fruit
trees are more valuable for starting an orchard than are older ones.
Apple and pear trees of this age will usually be straight switches, but.
others, as the peach and cherry, will have lateral branches. The
root system of the transplanted tree may need attention. Broken or
badly injured roots may be cut back to sound wood, and if one or
two roots are much longer than the others they should be cut back
to average length.
Straight-switch trees require only heading back at the time of
setting. A glance at figure 3 will make this operation plain. The
cut should be made a t a height of about 30 inches, thus allowing for
a trunk of 18 to 24 inches and sufficient space above it for the distribution of the framework branches. The pruned switch must bear a
number of good strong buds on the upper 12 inches. If these buds
are weak or have been rubbed off, the tree should be thrown away.
If two-year-old trees or branched yearlings are planted, they are
headed back a t about the same height as unbranched trees, though
the leader may be left somewhat longer if the branches below it are
vigorous and stocky. The framework branches are then chosen and
are headed back severely, to but one plump bud if the trees show
any signs of weakness, and all other branches are cut away close to
the main stock. Strong two-year-old trees having good root systems may be pruned in the manner described for “the second pruning,” except that the lateral branches should be more severly headed
back.
The Second Pruning.-After making its first summer’s growth
the young tree is again pruned during the dormant period. This is
the most important pruning that the tree will undergo. It involves
the choice of the framework branches of the future tree. These should
be three in number, of nearly equal strength, and well distributed
both around and up and down the main stem. After selecting those
to be left all other twigs are cut off close to the central stem. Those
preserved are then headed back to about 18 inches in length. The
central one of the twigs left on the tree will be upright in its growth
and will become the leader in the tree. It should be left slightly
longer than the other branches a t this pruning. Figure 4 illustrates
this operation.
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The Third Pruning.-One year later the tree will receive its
third pruning. This will be similar to the second and consist of both
thinning out of twigs and heading back of those which remain. These
latter will be about twice as numerous as the first series from which
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they arise, and are known as secondary branches. They should be
headed back in proportion to the growth they have made. Great
care must be exercised to space the branches as well apart on the
scaffold limb as is possible and to head them back to unequal lengths.
Many of these pairs of branches would form acute angled and weak
crotches if headed back to equal lengths. This difference in length
should be as much as six or eight inches. The secondary branches.
arising from the leader must be more severely cut back than the
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others and so selected as to fill the space between the first three
framework branches. Two or more may be allowed to remain, all
others being removed close to the leader. The leader is headed back
just a little higher than the tips of the other branches. The method
of the third pruning is shown in figure 5.
The Fourth Pruning.-The fourth pruning will follow the third
year’s growth in the orchard. It is, in general method, similar to
that of the preceding year and will result in an approximate
doubling of the number of branches in the tree. The same degree
of care must again be exercised in choosing the new twigs which are
to become permanent parts of the tree, t o avoid weak crotches and to
induce a symmetrical growth of the whole top. The leader will still
be allowed to persist but its tendency to outgrow the other branches
must be counteracted by heavier heading back and by leaving a
larger number of small twigs on it.
Later Prunings.-Subsequent prunings are similar to those described except that, as the time when the tree should begin to bear
fruit approaches, the general heading back of the twig growth will
be discontinued and the thinning out of branches will be restricted
t o those which are superfluous, grow across the tree, are diseased or
dead, or tend to throw the top of the tree out of balance by too
exuberant growth. At this stage the tree begins to develop fruit
spurs, if apple or pear, and will begin to set fruit buds, if peach.
The years between the ages of four and seven for early-bearing
kinds and varieties and six and nine for those which are later in coming into bearing are critical periods in the development of the trees.
Most growers wish to have the orchard come into bearing a t the
earliest possible age, and under favorable climatic and soil conditions
this is to be desired. There is, however, a general rule that a close
correspondence exists between the time a t which a fruit tree begins
to bear and the length of its productive life. Early bearing is linked
with early decline and late bearing with a long productive period. A
gradual change from pruning methods adapted to young trees to
those better suited t o bearing trees should be made during this period. It involves the substitution of branch removal for almost all
heading back and a general decrease in the relative amount of wood
removed.
Influence of Climate and Soil.-The fact that different kinds,
and even different varieties of the same kind, of fruit trees require
pruning methods adapted to their individual peculiarities, especially
while young, has been mentioned. Reference must also be made
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to two other factors which may still more strongly affect tree growth
habit; i.e., the climate and the soil.
Pruning to counteract deformity due to wind has been given much
study, but the opinion now seems to be general that a windbreak
is a better solution. Sunscald on the trunks and large branches of
young trees can usually be prevented by low heading and the avoidance of too heavy pruning. Soil exerts a dominant influence over
the shape of young trees. If the soil is fertile and the moisture
supply adequate the tree will make a rapid, vigorous wood growth
and may then be shaped to fit the grower’s ideal. But no amount or
any system of pruning can rectify bad shape in a tree which is making but a feeble growth due to infertile soil. The first step in correcting a poor habit of growth of a tree so situated is to supply it with an
abundance of plant food. After such treatment has stimulated the
tree into vigorous growth the usual pruning practices may be expected to succeed in bringing it to a proper shape.
PRUNING FOR TREE MAINTENANCE AND FRUIT PRODUCTION
This portion of the discussion of pruning relates in point of time
to the productive years in the life of the tree. The juvenile period
has passed and the objects which the grower then had in view no
longer govern; the vegetative stage has given way to the reproductive stage and pruning methods must be varied to correspond.
The New Objects.-Now that the fruit-bearing habit has been
established, the objects sought through pruning have taken on a
different character. First, maximum production of high-grade fruit
is desired. Second, the trees must make sufficient annual twig
growth to produce the needed leaves to nourish the fruit and maintain the vegetative vigor of the tree. Third, the size, including the
height, and the density of the tree must be regulated.
Pruning for Fruit Production.-The relative value of winter
and of summer pruning for the promotion of fruitfulness cannot be
fully discussed here. Results of experimental work on this problem,
carried on in many parts of the country, have been conflicting. It
seems best in the light of our present knowledge to do most of the
ordinary pruning while the trees are dormant. If summer pruning is
done, the time should be soon after the principal twig growth has
been completed and the method similar to that employed during the
dormant period. Pruning, whenever done, should be so performed
as to raise the grade of the fruit. It may assist in thinning the fruit.
thus increasing the average size, will result in much better color on
apples and peaches, and will, due to the more even admission of sun.
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light, delay the loss of spurs and bearing twigs on the interior of the
tree.
Pruning to Promote Vigor.-The use of pruning for the purpose
of increasing the vigor of fruit trees is limited. It forms a part of all
rejuvenation work but must be combined with soil improvement
measures and general good care to result in any lasting benefits.
That heavy pruning promotes vigorous wood growth on the pruned
parts of the tree is generally true, but it may a t the same time do
many other less desirable things.
Pruning to Regulate Size and Shape of Tree.-Maintenance
pruning is done, in large part, to keep the trees in proper size and
shape for both maximum and economical fruit production. The size,
in spread of branches, which orchard trees may be allowed to attain
is governed by the planting distance and the natural development of
the variety under the soil and climatic conditions prevailing in each
orchard. The planting distance should permit the trees to attain
their full horizontal growth without any interlacing of their branches
or undue interference with orchard operations, such as harvesting
and spraying. When such interference does arise the pruning, year
after year, must include some heading back of horizontal terminals to
confine each tree to its own area. The height must also be controlled. This is done by cutting the upright growing leaders back
to strong lateral growing branches. This prevents the formation of
a higher story in the tree, and should be so managed as to keep all
of the fruit-bearing wood within 20 feet of the ground.
Methods of Maintenance Pruning.-The actual operation of
maintenance pruning will differ from that previously described for
tree building in two main particulars; namely, the heading back of
twigs will have almost entirely ceased and the removal of large
branches will occasionally be necessary. I n the latter work, care
must always be exercised to make a neat, smooth wound and a t the
proper place. A large wound, smooth and so located that the sap
flow of the tree will reach all parts of its margin freely, will heal over
more quickly than a smaller one poorly made and located too far
from an abundant supply of food. Pruning “stubs” should never be
left. Care must also be taken when removing an upright-growing
branch to make the angle of the cut such as not to weaken the wood
to the extent that the weight of the lateral branch just below the
wound will later cause the main stem to split and break down at this
point. A light thinning out of small branches one to three years of
age will be needed at each pruning. This must be done to prevent
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the crowding of branches and to remove dead, diseased, broken, or
misplaced wood. These cuts should be made carefully and close to
the wood from which the branch is removed. The removal of all
watersprouts and sucker growth requires attention also. The latter
must be cut off close to the collar of the tree or the root and never at
the surface of the ground.
Relation of Pruning to Disease Control.-General directions on
pruning always recommend the removal of diseased branches. This
is usually good policy and needs emphasis but cannot be fully explained in this circular. It may be stated, however, that the more
important diseases the control of which involves pruning are fire
blight of the pear and apple, blister canker of the apple, and black
knot and pockets of the plum. Wood infected with any of these diseases should be removed well below the site of the lesion and the
prunings quickly and carefully burned. Bulletins which discuss the
control of these diseases should be consulted. For this type of pruning the disinfecting outfit described on page 15 should always be
available and used.
PRUNING TOOLS AND THEIR USE
Necessary equipment in the way of pruning tools needs be neither
complex nor expensive. It pays, however, to get the beet when buying such implements and then to take good care of them.
The Implements.-A supply of pruning tools for each workman
should include one swivel-back saw and a number of spare blades,
one pair of hand pruning shears, one pruning knife, a ladder, and a
disinfecting kit. Careful, experienced workmen may also find the
pole pruner or a pole saw a time-saving tool. Two-hand lopping
shears are popular tools with many pruners. Their use much expedites the removal of branches as large as one and one-half inches
in diameter. The best types of the tools are shown in figure 6.
The Proper Use of Pruning Tools.-The hand shears and the
knife are used to remove branches not more than three-fourths of
an inch in diameter. With either of these implements the work
can be better and more easily done if the left hand assists in making
the cut by keeping the tissue just ahead of the edge of the blade
under a strain. The knife is also used t o smooth off rough wounds
made by the saw or lopping shears. The saw may be used in removing all larger branches. The blade should be kept sharp and tight
and every care exercised to make smooth, even wounds, nearly
parallel with and close to the limb from which the branch is being
removed. Branches as large as one and one-half inches in diameter
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may be removed by the lopping shears. The pole pruner is used for
branches high in the tree or out a t the tips of the horizontal branches.
It should never be used in cutting branches more than three-fourths
of an inch in diameter. Practical pruners differ regarding the use of
the ladder, but one of the self-supporting type is a convenience and
lessens injury of the trees.
Equipment for Disinfecting.- Equipment for disinfecting,
wounds and pruning tools should always be a t hand if the presence
of fire blight or blister canker is even suspected in the orchard. The
outfit will consist of a wide-mouth bottle containing a 1 to 1,000
water solution of corrosive sublimate and cyanide of mercury, and a
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swab made by wrapping a number of thicknesses of cloth around the
end of a 12-inch stick. The swab is dipped in the disinfectant and
the blade of the pruning tool, as well as the wound, is thoroughly
moistened after removing a diseased limb and before starting work
on a new tree. This is much less bother than a description of it indicates, and should never be omitted. The chemicals may be obtained through any drug store and will have attached directions for
making the proper dilution. They are violent internal poisons, but
will not injure the skin of the hands by contact.
SOME SPECIFIC DIRECTIONS
PRUNING THE APPLE TREE
The foregoing discussion relates, in the main, to the pruning of
all kinds of deciduous fruit plants, although the apple has been more
particularly in the thought of the writer than have the others. Because of this, the statements applying specifically to the apple may
be made brief.
Apple trees are vigorous-growing plants, under proper environment, and require moderate annual pruning. The work is usually
done during the dormant period, a t any convenient time after the
leaves have fallen and before the spring flow of sap.
Fruit-bearing Habit.-The apple tree bears its fruit on short
crooked growths known as spurs. These are produced laterally on
branches a t least two years of age, bear the fruit from terminal buds,
and, if not starved or too heavily shaded, will continue to produce
for as many as ten or twelve years. Individual spurs tend to be
biennial in fruit bearing and when all the spurs on a tree produce
blossoms the same season the tree as a whole is likely to assume the
alternate habit. Pruning should be so managed as to prolong the
productive life of the fruit spurs by keeping the tops of the trees reasonably open to the sunlight. These spurs should never be pruned
off as long as they remain fruitful, except in case they are situated
directly on a large branch when the danger of their transmitting fire
blight to the framework of the tree may make it advisable to remove
them. Any pruner who insists on making the tree look neat by removing the fruit spurs should be given a thorough course of instruction, or at once dismissed.
Trunk and Framework.- Under Kansas conditions 18 to 24
inches seems to be the proper length for the trunk of an apple tree.
The first set of framework branches should be distributed over a
distance of about 12 inches above the trunk and should consist of
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three or four well-placed limbs. If a choice is possible, those
branches should be preserved which form a rather wide angle with
the trunk of the tree and are evenly spaced around it. Living ties
t o assist in strengthening weak crotches may be made in young trees
by twining together interior twigs from opposing limbs. The ends of
these twigs should not be cut off until after strong union has taken
place between them. I n the modified leader type of pruning additional main branches are allowed to arise from the leader until the
number reaches six or even more. These must be selected with care
that they may be strong and so placed as to make a symmetrical
tree. One or two is added each year until about the sixth year when
the leader is suppressed by cutting it off just above a strong lateral
branch. Care must be taken to keep the top twigs of the lower
framework branches nearly as high as those originating from the
leader.
Maintenance Pruning.-The pruning of bearing apple trees need
not be further discussed, as the preceding general remarks on that
topic apply particularly to this fruit. Moderate annual pruning,
such as will admit light to the center of the tree, prevent too great
height growth, assist in sustaining the vigor of the tree as indicated
by annual twig growth of six to twelve inches, and tend to promote
abundant fruit production, is what is required.
PRUNING THE PEAR TREE
The pear is a close botanical relative of the apple and bears its
fruit in much the same manner. Consequently, the same general
methods of pruning apply. Two differences do exist, however. The
habit of growth of most pear varieties is more upright than among
the apples and the fruits do not develop red color as do those of
many apple varieties. The first variation indicates that greater care
must be exercised to prevent the trees’ becoming too high, and the
second allows a somewhat more dense top to be tolerated. The
danger of shading out valuable, well-placed fruit spurs is to be
avoided as with the apple, however, and heavy pruning such as
would tend to promote a soft, vigorous twig growth is never desirable
because of the increased danger of fire blight attacks.
PRUNING THE PEACH TREE
The culture of the peach differs in many respects from that of the
apple, and at no point is this difference wider than in pruning. The
peach orchard should not be considered a permanent improvement
like an apple orchard. It should be pushed into early and heavy
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bearing and a new one started as soon as the old one begins to decline. The tree also differs from the apple in its general habit of
growth, the age a t which i t begins to bear, and in its fruit-bearing
habit.
Bearing Habit.-The peach tree, in general, bears its fruit from
axillary buds on twigs of the preceding summer's growth. If spurs
are produced, as does occur under some conditions and with some
varieties, they differ from apple spurs in that they are straight and
bear from lateral instead of terminal buds. Terminal buds on peach
trees are always vegetative in character. This difference in fruiting
habit indicates one of the principal distinctions between the pruning
of the apple and the peach. I n the former the twigs are of value, only
in the general vegetative economy of the tree, and any specific treatment of them does not immediately affect fruit production. But
with the latter the twigs have both vegetative and fruit-bearing
functions, and their removal or their failure to grow directly affects
t h e yield of fruit by the plant. (See figure 1 in this connection,)
The location of the fruit buds on the peach twig is variable. On
most young trees, and on some varieties at any age, they are developed well toward the tips of the twigs. As the trees become older
the fruit buds are formed lower on the twigs or distributed throughout the greater part of their length. The effect of this on pruning
operations is manifest; the thinning out of twigs always thins the
crop, but whether heading back does so or not depends on the location of the fruit buds, and must be made a matter of study in each
orchard a t pruning time.
Early Pruning.-Peach trees are usually bought from nurseries
a t one year of age. At that time the weak ones may be straight
switches, but the more vigorous ones are likely to have lateral
branches. The pruning a t the time of setting will consist of heading
back either type of tree a t a height of 18 to 24 inches. Care must
be taken to make sure there are good strong buds on the upper part
of the stub which is left, and this requirement will sometimes necessitate leaving lateral branches bearing two or three buds, or occasionally, higher heading.
During the dormant period following the first summer's growth the
trees should be given their second pruning. This will agree with the
general directions (page 8) but will involve more severe heading
back of the framework branches than with other kinds of fruit trees.
The length left need not be more than one foot. Should the second
or third season's growth of twigs show a set of fruit buds, which will
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be found as additional buds in the axils of the leaves and on one or
both sides of the branch buds, the grower has a choice in methods of
pruning. All twigs not needed for permanent parts of the tree may
be cut away and those left severely headed back. This will build
up the strongest tree possible but will sacrifice nearly all of the first
crop of fruit. The other method is t o leave a considerable number
of twigs which are not needed as permanent parts of the tree and
head them back but slightly. These excess twigs will produce fruit
that season and should be cut out entirely the following winter.
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Permanent branches left a t the same time should be headed back,
usually below the region where they bear fruit buds, and thus prevented from moving the bearing wood of the future too far from the
ground.
The exact extent of heading back to be practiced in pruning young
peach trees must be determined through local experience. The principal point to bear in mind is that too severe heading back delays
fruit-bearing while too light produces high, “leggy” trees (fig. 7)
which make all orchard operations more expensive. Making a correct decision in this dilemma constitutes the real test of the pruner’s
skill.
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Pruning Older Trees.-As peach trees approach maturity constant care must be exercised to keep the tops open to the sunlight.
If this is done by judicious annual thinning out of young wood, the
tree will be kept low in stature and vigorous bearing wood will be
retained in the lower interior parts of it. Low-hanging peach
branches are of but little value. The fruit they may bear is poor in
‘quality and color. Hence the pruner’s attempt should be to keep
the shape of the tree such that the framework branches will be somewhat upright, forming an angle of about 45 degrees with the central
shaft of the tree. The top should be kept well open to sunlight and
spray materials. All leaders should be subdued and their vigor directed into more horizontal growths.
Deheading.-Under certain conditions money has been made by
“deheading” old peach trees and inducing them t o grow new tops.
This is usually done following a severe winter which kills the fruit
buds. It consists in cutting all of the top of the tree back t o the
secondary branches as is illustrated in figure 8. Growth the following summer may be abundant and vigorous, may be confined to only
certain branches, or may fail entirely. When abundant, it will require severe thinning out and heading back during the dormant
period and probably will produce fruit buds the second summer following the deheading. Because of this certain loss of two crops and
t h e possibility of the death of the trees, serious consideration should
always be given the question whether it would not be better to grow
a new orchard and, upon its reaching bearing age, remove the old
one without attempting to rejuvenate it.
PRUNING THE SOUR CHERRY TREE
Of all the deciduous fruit trees grown in Kansas the sour cherry
requires the least pruning, especially when it is grown on Mahaleb
stocks and when the low spreading varieties are planted. However,
the sweet cherry and the more upright growing sour varieties on
Mazzard stocks require constant attention in order to prevent their
becoming too tall for economical fruit harvesting.
Pruning Practice.-One-year-old sour cherry trees are likely to
have developed lateral branches in the nursery and the choice of the
framework limbs is made a t the time the tree is planted in the
orchard, which should be as early in the spring as is possible and on
fall-plowed land.
The principles underlying the choice of framework branches for
these plants do not differ from those already described except that
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it is customary to leave a larger number than with other fruit trees,
some growers recommending as many as seven. A trunk not more
than 18 inches in length is best. The branches left to form the framework may be rather severely headed back. Subsequent pruning
throughout the life of the tree will consist of thinning out clusters
of twigs which develop near the tips of the preceding year’s growth,
the removal of crossing, rubbing, and parallel branches and all water
sprouts and suckers, and the suppression of any branches which show
a tendency to grow too high. This, with the removal of diseased or
dead branches, is usually all that is needed, though some heading
back of the twigs may be desirable while the trees are young.
Fruit-bearing Habit.-The sour cherry bears fruit on spurs and
also in the axils of the leaves on one-year-old wood. The spurs,
however, are straight, the terminal bud being vegetative, in contrast
with the crooked spurs and terminal fruit buds of the apple. The
distribution of fruit-bearing between these two types of organs is a
characteristic of varieties and should be given study by the grower.
If fruit is borne on the twigs any heading back may be a thinning
process. The maintenance of the vigor of the spurs through keeping
the top of the tree open is also important.
PRUNING THE PLUM TREE
Plum trees bear their fruit on both spurs and twigs, the relative
amounts produced in each location being characteristic of the
variety. This fruit does not require intense sunlight for the development of its color, but the top of the tree must be kept fairly open to
maintain the vigor of the lower and interior branches.
The Method.-Five or six framework branches are usually developed on the plum tree. These are headed back as are also later
permanent branches low in the tree, but after a well-balanced tree
has been grown the need for heading back or, in fact, any save corrective pruning, ceases. A top not too dense but low and broad in
shape is desired.
PRUNING THE BUSH FRUIT PLANTS
The pomological group known as the bush fruits includes blackberries, raspberries, gooseberries, and currants. With reference to
their fruit-bearing habit and method of pruning used with them,
they fall into pairs, the first two and the last two belonging together.
Fruit-bearing Habit.-Blackberries and raspberries bear all
their fruit on canes of the preceding summer’s growth. These canes
carry no separate fruit buds over the winter but bloom on shoots of
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the current season’s growth. The fruit of the currant and the gooseberry is borne principally on spurs which are found on wood of considerable age but which remains vigorous and productive for only
three or four years.
Pruning Methods.-All of the small fruit plants should be
pruned back severely when they are set out, but more especially the
raspberry and the blackberry, on which but one cane bearing two to
five buds should be left. Two or three canes may be saved from the
first summer’s growth if the plants are vigorous, but weak plants
should again be reduced to a single cane. The annual pruning during the remainder of the life of the patch will include: (1) The removal of all the canes which have borne fruit; (2) the reduction of
the number of new canes to that which the plant can support through
fruit production-between five and ten, depending on the fertility of
the soil and the moisture supply; (3) the heading back of these canes
to adapt them to the system of training followed; (4) the pinching
out of the growing tip of the canes just when they reach a height of
18 inches if no trellis is used and the plants are to be self supporting.
All suckers which arise from the roots between plants must be dug
out, but this is a cultivation problem rather than one for the pruner.
The general system of pruning the gooseberry and currant plants
is similar to that sketched above except that the old bearing wood
is removed each third year instead of each year. Each plant may
contain about six canes, the oldest two of which are annually cut
away and replaced by two new shoots of that year’s growth, these
to be allowed to bear three crops when they in turn are removed.
All new shoots in excess of those needed to replace old canes are
pruned out close to the crown of the plant.